Immersion type thermostat



Jan. 2, 1940. v. o. BEAM IMMERSION TYPE THERMOSTAT Filed 0G12. 8, 1957 PatentedJan. 2, 194i) uNlTED STAT-Es PATENT OFFICE IMMERSION TYPE THERMOSTAT" Vilynn 0.' Beam, Cleveland Heights, Ohio, assignor to The Bryant `Heater Company, (lleve` land, Ohio, a corporation oi' Ohio y `\\Application October 8, 1937, Serial No. 168,003

2 Claims. V(Cl. 20o-137) This invention relates to a thermostat of the immersion type adapted to control the temperature in a heating plant, such as a boiler or furnace, or like equipment.

The principal object of the invention is to provide a thermostat of this .character which is simple in construction, efiicient and reliable in operation, rugged, readily applied, and easily adjusted to vary the temperature at which the device functions.

In the accompanying sheet of drawings wherein I have shown an embodiment which operates very effectively,

Fig. 1 is a vertical sectional View of'the ther- 'mostat;

Fig. 2 is a front view; and

Fig. 3 is a fragmentary sectional view sub-w stantially along the irregular line 3 3 of Fig. 1. 'I'he `thermostat includes a metal housing I0 on the "interior of which is supported an electric switch I I which may be of any suitable construction, but generallyconsists of a switch blade which is adapted to be moved into or out of engagement with a xed contact. At the' bottom of the housing is an opening I2 through which' the conductors'of the circuit controlled by the switchA are extended into the housing and connected to the switch.

Screwed into' an internally threaded boss I3 on the rear wall of the housing is a fitting I4 having a reduced externally threaded rear portion I5 by which the device is adapted to be fixed in the wall of the boiler or tank. This fit- ,ting additionally forms the main support for a range of temperatures at which the instrument Dis adapted to function. I'ngthiswinstance the rod I'I is fixed to the outer end of the tube I6, and this is preferably done by solidly screwing the rearend of rod l1 in a"bu"shing'is secured in the outer end of tube I6 and then sealing the outer end of the tube beyond the bushing with solder or other readily fusible metal or alloy I9. A cap 20 may be fitted onto the extreme outer end of the-tube I6. To insure a leakproof jointv between the tube and the fitting I4, after the tube is screwed into the rear end of the fitting the joint may be sealed against leakage by solder indicated at 2|.

The rod I1 extends beyond the tube and its forward end is threaded into a shaft 22 which extends horizontally across the housing, its rear` 5 end extending freely into the bore of the fitting I4 and its forward end being supported and' journaled in a boss 23 inthe front Wall of the housing I0. The shaft 22 has a reducedend which extends forwardly beyond the front wall 10 of the housing and secured to its forward end is an adjusting knob 24 bywhich the shaft 22 may be turned on the threaded end of rod Il to move the former forwardly or-rearwardlyand thereby adjust vthe instrument for different temperatures. The knob 24 has a pointer cooperating with ascale 25 at the upper part of a plate 26 secured to the front wall of thehousing.-

As the temperature of the, medium in which the element is immersed rises, the tube I6 pulls 20 the relatively inexpansible rod I1 rearwardly and with it moves the shaft 22. 'Ihis movement is utilized to actuate the switch II, and for that purpose I provide a switch operating member in the form of an angle lever orl bell vcrank 21 26 which is connected by a flexible spring hinge 28 to the front wall of the housing'of the switch II and has a substantially horizontal arm extending over the switch in position to actuate a switch operating pin 29 extending through the 8. top wall of the switch housing. Additionally, this bell crank has an arm 2lb extendingsubstantially vertically, this arm being notched at its upper end thus forming a yoke 21o which fits into a reduced portion 22a of the shaft 22. The 3l upstanding arm 21h is preferably slightly bowed and bears against a shoulder 22h at the forward end of the reduced part 22a.

Y The operation is as follows: The knob 24 will be set so that the instrument will function at 40 the desired high temperature. This, as before stated,- can be varied by turning the knob 24 which adjusts the position of the shaft 22 andits shoulder 22h with reference to the upstanding arm'of the bell crank 2l. As the tempera- 45 tu're rises, the tube I 6 expands lengthwise, pulling the relatively inexpansible rod I'I rearwardlyv with it. This moves the shaft 22 inwardly or rearwardly, there being sufficient clearancebetween the.knob and the plate25 to permit this I0 movement,and, after a predetermined movement, the switch operating bell crank 21 is` vrocked so as to sufiiciently depress the pin 29' to actuate the switch. Generally this movement opens the switch. as when the switch is utilized I boiler. Commonly, the switch operates the circuit of a solenoid which controls a main gas valve when the furnace or boiler is heated with gas, but it may control some other instrumentality when a different type of fuel is used.

Furthermore, by employing a reverse action switch, i. e'., one which is closed by the rocking of the bell crank due to heating of the thermal element, the instrument may be employed, for example, to start a fan in a warm air system.

Obviously, when the temperature falls, the tube I6 contracts, moving forwardly the rod l1 and the shaft 22 and allowing the spring hinge 28 to restore the bell crank to its previous off position and to allow the switch to automatically return to its previous closed or open position, as the case may be.

While I have shown the preferred construction, I do not desire to be confined to the precise details shown but aim in my claims to cover al1 modifications which do not involve a departure from the spirit and scope of the invention.

Having -thus described my invention, I claimtv` 1. In a thermostat of the character described, a housing, a thermal element projecting from the rear Wall of the housing composed of an outer'tubular member and an inner rod having diierent coeiilcients of expansion, the tubular member lbeing secured to the housing andthe rod being secured to the outer end of the tubular member and projecting therethrough into the housing, threads on the inner end of said rod,

l 9,186,623 to control the supply of fuel to the furnace or a control elementaxially aligned with said rod and having a threaded socket to receive the threaded end of the rod and projecting at its forward end through the front wall of the housing a switch in the housing offset from said rod and control element, an annular shoulder on said control element within the housing, an operating connection between said switch and control element arranged to bear upon said shoulder, and spring means for maintaining said operating connection in engagement with said shoulder.

2. In a thermostat of the character described, a housing, a thermal element projecting from the rear wall of the housing composed of an outer tubular member and an inner rod having different coefilcients of expansion, the tubular member being secured to the housing and the rod being secured to the outer end of the tubular member and projecting therethrough into the housing, threads on the inner end of said rod, a control element axially aligned with said rod and having a threaded socket to receive the threaded end of the rod and projecting at its forward end through the front wall of the housing, a switch in the housing offset from said rod and control element, an annular shoulder on said control element Within the housing, and an angular operating lever pivotally mounted in the housing arranged to engagesaid shoulder in all rotary positions of the control element and arl ranged to engage and operate said switch.

vILYNN o'. BEAM. 

